Field of the Invention
The invention relates to an image-sensor structure, and more particularly to an image-sensor structure with color filter patterns containing high/low-refractive-index components.
Description of the Related Art
An image sensor, as a kind of semiconductor device, transforms optical images into electrical signals. Image sensors can be generally classified into charge coupled devices (CCDs) and complementary metal oxide semiconductor (CMOS) image sensors. Among these image sensors, a CMOS image sensor comprises a photodiode for detecting incident light and transforming it into electrical signals, and logic circuits for transmitting and processing the electrical signals.
In an image sensor, in order to increase sensitivity of a color filter material, an appropriate color filter material is selected to fit the expected target spectrum of the color filters. However, device performance such as SNR (signal-to-noise ratio) or quantum efficiency (QE) cannot achieve optimization only by fitting the expected target spectrum of the color filters due to the interaction between the color filter materials.
Therefore, development of novel color filters with an adjustable refractive index (which considers the issue of the interaction between the color filter materials) which can improve device performance such as SNR (signal-to-noise ratio) or quantum efficiency (QE) is desirable.